Wrappers for many more POSIX functions in the “os” and “signal”
modules, as well as other useful functions such as “sendfile()”

Hash randomization, introduced in earlier bugfix releases, is now
switched on by default

* PEP 380, syntax for delegating to a subgenerator (“yield from”)
* PEP 393, flexible string representation (doing away with the
distinction between “wide” and “narrow” Unicode builds)
* A C implementation of the “decimal” module, with up to 80x speedup
for decimal-heavy applications
* The import system (__import__) now based on importlib by
default
* The new “lzma” module with LZMA/XZ support
* PEP 397, a Python launcher for Windows
* PEP 405, virtual environment support in core
* PEP 420, namespace package support
* PEP 3151, reworking the OS and IO exception hierarchy
* PEP 3155, qualified name for classes and functions
* PEP 409, suppressing exception context
* PEP 414, explicit Unicode literals to help with porting
* PEP 418, extended platform-independent clocks in the “time” module
* PEP 412, a new key-sharing dictionary implementation that
significantly saves memory for object-oriented code
* PEP 362, the function-signature object
* The new “faulthandler” module that helps diagnosing crashes
* The new “unittest.mock” module
* The new “ipaddress” module
* The “sys.implementation” attribute
* A policy framework for the email package, with a provisional (see PEP
411) policy that adds much improved unicode support for email header
parsing
* A “collections.ChainMap” class for linking mappings to a single
unit
* Wrappers for many more POSIX functions in the “os” and “signal”
modules, as well as other useful functions such as “sendfile()”
* Hash randomization, introduced in earlier bugfix releases, is now
switched on by default

值得注意的更新内容如下：

详细改进内容：

新语法特性:

下载地址：

Python 3.4 并未添加任何新的语法特性

(文/开源中国)

其他新特性:

pip should always be
available
(PEP 453).

Newly created file descriptors are
non-inheritable(PEP
446).

command line option for isolated
mode(issue
16499).

improvements in the handling of
codecsthat
are not text encodings (multiple issues).

A ModuleSpec
Type
for the Import System (PEP
451). (Affects importer
authors.)

Themarshal
format has been made more compact and
efficient
(issue 16475).

Retrieving certificates from the Windows system cert store
support
for ssl.

Server-side SNI (Server Name Indication)
support
for ssl.

Thessl.SSLContext
class has a lot of
improvements.

All modules in the standard library that support SSL now support
server certificate verification, including hostname matching
(ssl.match_hostname())
and CRLs (Certificate Revocation lists,
seessl.SSLContext.load_verify_locations()).

CPython 实现改进:

Safe object
finalization
(PEP 442).

Leveraging PEP 442,
in most cases module globals are no longer set to None during
finalization
(issue 18214).